Inserted tooth milling cutter



June l2, 1945. R. D. GRAYsoN 2,378,215

INSERTED TOOTH MILLING CUTTER Filed April 3, 1944 fave/'L hara myfa Patented June 12, 1945 INsEn'rED'rooTH MILLING CUTTER f i l Richard D. Grayson, Monrovia, Calif., assigner, by mesne assignments, to Lowell & Grayson, Monrovia, Calif., a` limited partnership Application April 3, 1944, Serial No.` 529,282

9 Claims.

This invention relates to milling cutters of the inserted tooth type disclosed inthe co-pending applicationof Edward O. Lowell, Serial No. 493,- 815, iiled July 8, 1943.

The principal object of my invention is to provide a milling cutter of the kind mentioned, so designed and constructed that the inserted teeth may be adjusted, removed and replaced easily,`

and are arranged to be locked and held in place so that they are extremely rigid and there is no likelihood of vibration, freedom from vibration being particularly important where the inserted teeth are tipped with tungsten carbide or any of the other sintered carbides, because these materials are hard but not tough, and .while possessing extraordinary resistance to wear, are easily broken down if subjected to excessive vibration.

The milling cutter disclosed in the Lowell application has precision flat contacting surfaces on the backs of the inserted teeth and the cooperating back walls of the' slots, such contact,

' clined with respect to the radii accordingly. The

teeth may also be inclined relative to the axis;if desired. The periphery of the body is cut away in front of each slot I3, as' at I5, for chip clearance, but the peripheral portion I6 of the body behind each slot is not cut away, whereby to provide greater "precision flat bearing surface at I'I forgood rigid support of the inserted teeth I4, these teeth 'being provided with precision at back surfaces I8 for contact with the at back walls I'I of the slots. In accordance with the Lowell application, the front wall of each slot yhas wedge lock serrations I9` provided therein to intert in wedge lock serrations provided in the 20 front face ofthe tooth I4 inserted in the slot.

together with the secure wedge-locking action of intertting serrations on the iront surfaces of the inserted teeth and the front walls of the slots making for good rigidity, and eliminating danger of vibration of the ,inserted teeth when the inserted teeth are forced substantially radially outwardly by the tightening of a screw or screws in the teeth, against the inner ends of the slots.

A salient feature of my improved milling cutter lies in the provision of screws of novel design which, although operable through relatively small openings in the top portions of the inserted teeth by an adjusting wrench, are large enough in di- A ameter to assume thethrust imposed thereon and have venlargedlower end portions for engagement with the inner end of the slots so as to reduce likelihood of forming depressions in the inner ends of the slots, the increased area of contact vbetween the screw and slot giving increased assurance of rigidity, generally. The invention is illustrated in the accompanying drawing, in which Fig. 1 is a side View of a milling cutter-made in accordance with my invention;

Fig. 2 is an enlarged detail ofthe cutter, showing one of the inserted teethin section, and

require regrinding, the teeth can be removed and replaced vone or more serrations removed from the original setting and then fastened in the new setting. A pair of set screws 2i is provided in each tooth threaded in holes 22 parallel to one another andlto the iiat back face I 8 of the tooth and the serrated front face 20 but substantially at right angles to the direction of said'serrations, and these screws are provided with sockets 23 in their outer ends for'application of a wrench, and l are arranged to be tightenedA against the flat inner .end wall 24 of the slot. In the tightening of theL screws the slight clearance in the'interfitting serrations I S and 2U is taken up and the tooth is forced bodily against the back wall Il of the slot with great pressure, 'and the tooth is therefore held firmly in place with great rigidity and there is no danger of excessive vibration during operation. '1 refer to these serrations as of the buttress type because of the resemblance to the shape of buttress threads, butwant to point out that whereas a buttress threadexerts force with minlmu'm wedging` and friction in relation to screw I pressure, the serrations I9-20 are intended to give Fig. 3 is a plan View of the tooth shown in Fig. 2.

The same reference numerals are applied to lcorresponding parts in these three views.

Referring rst to Fig. 1, the reference numeral thel usual center hole II .and key slot I2. .A

the opposite eiiect and provide maximum wedging and friction in relation to the force exerted by 4the set screws. Centrifugal force is also an important `factor tending to tighten the inserted f teeth and make for greater rigidity and incidentallygreater safety. The `flat face contact'at Vplurality lof substantially radial slots I3 are pro- 55 II-I8 isparticularly important from the standpoint of rigidity, because, as should be clear, dat surfaces such as these may be produced very accurately, whereas it is not practical to cut the serrations as accurately, and in many previous constructions which require the provision of interfitting serrations on the backs of the teeth and The inserted teeth I4 in accordance with mv invention, have relatively -small holes 26 provided in the outer end portions lthereof, co-axial with and extending from the :outer aend oi the threaded holes 22. In other words, the screws ,2l are large enough in diameter to assume the thrust imposed I thereon, and the holes 26 are relatively small and only large enough for the ,insertion of an adjusting wrench to be entered in the sockets 23 in the outer ends of the screws. Reduction in the size oi the .holes 26 .is important from the standpoint that sulcient metal is left in ithe inserted teeth for vrigidity and resistance to impact. The screws have shcrtsmooth :shank portions :21 on their inner ends, terminating in enlarged conical,A flat- `bottom base portions 228 -ior :increased area of .iflat surface-to-surface engagement with the .iiat .inner end walls 24 of the slots, In -that way there 'is `little or no likelihood of forming depressions in the bottom of the slots, and the increased width of fiat surface-to-surface abutment between the screws and the bottom of the slots :makes for greater rigidity rand decreases likelihood .of vibration during operation. The inner ends of the holes 22 are flared, as indicated 'at 29, to lafford clearance for the conical .base portions 2B vof vthe screws. l

It should be clear from the foregoing description that I have provided Va milling cutter of extremely simple and practical construction, and one which insures the desired .rigidity .and freedom ifrom vibration for the inserted teeth, without, however, sacrificing convenience of adjustment of the inserted teet'hto maintain a-diameter after grinding operations. The substantial 'area of contact between the set screws and the inserted teeth, taken together with the increased area tof contact lbetween the base portions vof the screws and the bottoms of :the slots, ina-ke Vfor maximum 'rigidity of the inserted teeth, besides 'reducing the likelihood of thescrews lforming depressions in the cutter-body.

It is Abelieved the foregoing Aidescriptirm conveys a good understamiingof the objects Asand advantages of my invention. .The appendedclaims have vbeen drawn with a view to covering ell legitimate modifications and adaptations.

I'claim': 1. In aml'llingcutter of `Vthe inserted tooth type,

the combination of a body member having fone or more peripheral slots provided therein, `inserted tooth cutting ymembersdisposed-in said slots, each having means on at leastnne side face adapted `to 'have locking engagement with -the adjacent .side

wall ofthe slot to 'prevent displacement `radially relative to the bod-y and also having a relatively the cutting member in place in the slot, the bottom portion oi said screw ,beingrenlarged in relation to the pitch diameter of said screw, whereby to reduce likelihood of the screw forming any depressionin the bottom of the slot.

2. .In a.milling cutter of the inserted tooth type,

the combination of a body member having one or more peripheral slots provided therein, inserted tooth cutting members disposed in said slots, each having means on at least one side face adapted to have locking engagement with the adjacent side wall of the slot to prevent displacement 'radially relative to the body and also having a through-hole provided therein ,from top ,to bottom, an adjustable screw threaded in said hole and adapted t' be adjusted into abutment with the bottom of the slot to lock the cutting member in place in the slot, the bottom portion of said screw being enlarged in .relation to the .pitch diameter of said screw, whereby .to reduce likelihood of the screw forming any depression in the bottom of the slot.

3. A milling cutter of the inserted tooth type, comprising a rotatable body member provided with a substantially radial tooth receiving slot, a tooth in said slot, interiitting serrations on a wall of the slot and the adjacent 4iace of the tooth, said serrations extending in the direction of the axis of rotation of .the body, whereby the tooth is insertible and removable 'by .movement laterally with respect to the body, and Aone or more fastening screws threaded in through-.holes provided in the tooth in transverse relation to said serrations, said screws being 4threadalble into enga-gement with the inner end oi the .slot to force the interfitting serrations into wedging engagement, the outer end of each of said throughholes being of relatively small diameter `adapted for the insertion of .an adjusting wrench, the

screw lbeing of relatively larger diameter yand threading in the enlarged 'inner end vportion of the hole, the inner end base yportion `of thescrew being enlarged in relation to the pitch .diameter oi the screw., whereby to reduce likelihood of the screw forming any depression in the inner end of the slot.

4. A milling cutter of the inserted tooth type,

l comprising a rotatable body member provided with a substantially radial tooth receiving slot, a tooth in said slot, interntting .serrations on a. wall o the slot and the adjacent :tace .ofthe tooth, said serrations extending in the direction of the axis oi rotation of the body, whereby the tooth .is insertible and removable by movement laterally with respect to the lbody.,..and one or more fastening screws threaded in through-holes provided in the tooth in transverse relation .to said serra-tions, .said screws 'beingthreadab'le :into engagement' with the Ainner end oi the slot to force the .intertting serrations kinto wedgingengagement, the inner end base ,portion of each screw being enlarged in relation to the ,pitch diameter of the screw, whereby to reduce likelihood oi .the screw forming any depression inthe inner .end of the slot.

J5.; In a tool holder, the combination of abody having ,a substantially radial .slot l.provided therein, a cutting tool adapted to be entered 'in said slot and having means on one side face for locking engagement in the adjacent side wall of the slot to prevent radial displacement from the slot, the cutting tool having a through-hole provided therein from top to bottom, the outer end vportion of which is of relatively small diameter adapted for the insertion cf an adjusting wrench, an adjustable screw of relatively larger diameter threaded in the enlarged inner end portion of said hole and adapted to be adjusted into abutment with the bottom of the slot to lock the cutting tool in place in the slot, the inner end portion of the screw being enlarged, whereby to,reduce likelihood of the screw forming any depression in the bottom of the slot.

6. In a tool holder, the combination of a body having a substantially radial slot provided therein, a cutting tool adapted to be entered in said slot and having means on one side face for locking engagement in the adjacent side wall of the slot to prevent radial displacement from the slot, the cutting tool having a through-hole provided therein from top to bottom, an adjustable screw threaded in said hole and adapte to be adjusted into abutment with the bottom of he slot to lock the cutting tool in 'place in the slot, the inner end portion of the screw being enlarged, whereby to reduce likelihood of the screw forming any depression in the bottom of the slot.

7. In a milling cutter of the inserted tooth type, wherein each cutting member is disposed f in a peripheral slot provided in the body of the cutter and has means on at least one side face adapted to have looking engagement with means on the adjacent side w'all of the slot to prevent displacement of the cutting member radially rel- A ative to the body, and wherein each cutting member has a substantially radially extending opening provided therein, the upper end of which is accessible from the top of the cutting memiber, means for clamping each of said cutting members comprising a headless screw having a threaded shank threaded in the radial hole in the cutting member and terminating in an abutment end portion adjacent the inner end of lsaid hole substantially larger than the pitch diameter of the thread to increase the area of its abutment and accordingly decrease the likelihood of forming depressions in the surface abutted thereby in the inner end of the slot in said cutter body, and means on the opposite end of the screw whereby said screw may be turned.

y 8. In a milling 'cutter' of the inserted toothv type, wherein each cutting member is disposed in a peripheral slot provided in the body of the cutter and has means on at least one side face adapted to` have locking engagement with means on the adjacentside wall of the slot to prevent displacement of the cutting member radially relative to the body, and wherein each cutting member has a substantially radially extending opening provided therein, the upper end of which is accessible from the top of the cutting member,

means for clamping each of said cutting members comprising a headless metal screw adapted to be threaded in the radial hole in the cutting member, the inner abutment end of the screw being of enlarged diameter, substantially larger than the pitch diameter of the screw, the lsaid screw having a non-circular socket in the outer end coaxially with respect to the screw and substantially smaller than the pitch diameter there- 'of adapted to receive a driving means for adjustment of the screw.

9. In a milling cutterof the inserted tooth type, wherein each cutting member is disposed in a peripheral slot provided in the body of the cutter and has means on at least one side face adapted to have .locking engagement with means on the adjacent side wall of the slot to prevent displacement of the cutting member radially relative to the body, and wherein each cutting member has a substantially radially extending opening provided therein, the upper end of which is accessible from the top of Jthe cutting member, means for clamping each of said cutting members comprising a headless metal screw adapted to ,.be threaded in the radial hole in the cutting member, the inner abutment end of the screw being of lenlarged diameter, substantially larger than the pitch diameter of the screw, the said screw having a non-circular 'socket in the outer end icoaxially with respect to the screw and substantially smaller` than the pitch diameter thereof adapted to receive aidriving means for adjustment of the screw, the cutting member having a reduced bore in coaxial relation to said socket opening from the outer end of the threaded bore adapted for insertion therethrough of the screw driving means.

RICHARD D. GRAYsoN. 

